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Coffee and Cancer

On a recent flight from London to Los Angeles, I was asked a question that comes up rather frequently in my line of work: Should coffee be avoided because it’s acidic and, therefore, promotes cancer? The basis for this inquiry is almost always sensational information found in select books, magazines or websites advancing the theory that good health depends on a proper balance of acid and alkaline forming foods in one’s diet. In most instances, the proponents of this hypothesis claim that an overly acidic diet contributes to lower systemic oxygen levels which, in turn, provides a fertile breeding ground for cancerous cells.

Coffee is universally included on lists of so-called “acid forming” foods. But, if coffee does indeed promote an acidic environment in the body and, thereby, stimulates the growth of malignant cells, you’d expect to find evidence of this fact in the scientific literature. After all, nutritionists are always on the lookout for dietary and lifestyle patterns which may increase or lower the risk of cancer. And, let’s face it, coffee isn’t exactly a darling of the medical or nutritional communities because of caffeine content, over use and relative lack of nutritional components.

Over the past few years, a slew of reviews and studies reveal that coffee consumption does not increase the risk of virtually any cancer. The neutral affect of coffee in relation to cancer has been established in various malignancies including breast, ovarian, and pancreatic cancer. The findings for lung cancer have been mixed. One study found an elevated risk in coffee drinkers. But, several other investigations found the opposite to be true. And finally, a number of common and rare malignancies such as brain (glioma), endometrial, liver, oral and prostate cancer appear to be less prevalent and/or less aggressive in those who frequently consume decaffeinated or regular coffee. There was even a comprehensive review in the March 2011 issue of the prestigious journal BMC Cancer which concluded that, “Findings from this meta-analysis suggest that coffee consumption may reduce the total cancer incidence and it also has an inverse association with some type of cancers”.

I have no problem with the inclusion of more “alkalizing” foods in most dietary regimens. In fact, I believe this would likely reduce the overall disease burden in the population at large. Many of the foods that are commonly recommended to balance pH are very healthful and nutrient dense – green leafy and other non-starchy vegetables, low glycemic fruits, nuts and seeds, etc. However, I take issue with those who unjustly malign controversial beverages and foods that can often be enjoyed in a health promoting and reasonable manner. The bottom line is this: Based on the current evidence available, there’s no need for coffee lovers to abandon their beloved brew for fear that it is carcinogenic. On the other hand, if you enjoy coffee and have been avoiding it, there may be good cause to have an occasional cup if you tolerate it well.

Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!

To learn more about the studies referenced in today’s column, please click on the following links:

15 Comments & Updates to “Coffee and Cancer”

Hi JP,
What do you think of the whole “alkalizing/pH balancing” trend in
supplements and with cleanses and diet? It has always seemed like a good example of “a little learning is a dangerous thing” – taking a basic concept and exaggerating it all out of proportion. Since pH varies depending what part of the body or what body fluids you are talking about, I’ve never quite understand overall
pH balancing – especially since the body pretty tightly “balances” it already. Are they usually referring to pH of the blood?

I have mixed feelings about it. On the one hand, I think that most people are perfectly capable of maintaining their pH within a normal range without assistance. Having said that, I have encountered some who appear to benefit from pH balancing supplements/water and the like. My hunch is that most, if not all, of these cases have more to do with the mineral supply provided by said products. In other words, mineral deficiency is a more likely explanation, IMO.

Saliva and urine pH is what’s usually measured – because it can be easily assessed using test strips in a home or office setting.

This meta-analysis was conducted to assess the association between coffee consumption and prostate cancer risk. Thirteen cohort studies with 34,105 cases and 539,577 participants were included in the meta-analysis. The summary relative risks (RRs) with 95% confidence intervals (CIs) for different coffee intake levels were calculated. Dose-response relationship was assessed using generalized least square trend estimation. The pooled RR for the highest vs. lowest coffee intake was 0.90 (95% CI: 0.85-0.95), with no significant heterogeneity across studies (P = 0.267; I2= 17.5%). The dose-response analysis showed a lower cancer risk decreased by 2.5% (RR = 0.975; 95% CI: 0.957-0.995) for every 2 cups/day increment in coffee consumption. Stratifying by geographic region, there was a statistically significant protective influence of coffee on prostate cancer risk among European populations. In subgroup analysis of prostate cancer grade, the summary RRs were 0.89 (95% CI: 0.83-0.96) for nonadvanced, 0.82 (95% CI: 0.61-1.10) for advanced and 0.76 (95% CI: 0.55-1.06) for fatal diseases. Our findings suggest that coffee consumption may be associated with a reduced risk of prostate cancer and it also has an inverse association with nonadvanced prostate cancer. Because of the limited number of studies, more prospective studies with large sample size are needed to confirm this association.

Purpose: Epidemiologic studies indicate that dietary factors, such as coffee, may influence breast cancer and modulate hormone receptor status. The purpose of this translational study was to investigate how coffee may affect breast cancer growth in relation to estrogen receptor-α (ER) status.

Experimental Design: The influence of coffee consumption on patient and tumor characteristics and disease-free survival was assessed in a population-based cohort of 1,090 patients with invasive primary breast cancer in Sweden. Cellular and molecular effects by the coffee constituents caffeine and caffeic acid were evaluated in ER+ (MCF-7) and ER− (MDA-MB-231) breast cancer cells.

Associations of coffee drinking with systemic immune and inflammatory markers.

BACKGROUND: Coffee drinking has been inversely associated with mortality as well as cancers of the endometrium, colon, skin, prostate, and liver. Improved insulin sensitivity and reduced inflammation are among the hypothesized mechanisms by which coffee drinking may affect cancer risk; however, associations between coffee drinking and systemic levels of immune and inflammatory markers have not been well characterized.

METHODS: We used Luminex bead-based assays to measure serum levels of 77 immune and inflammatory markers in 1,728 older non-Hispanic Whites. Usual coffee intake was self-reported using a food frequency questionnaire. We used weighted multivariable logistic regression models to examine associations between coffee and dichotomized marker levels. We conducted statistical trend tests by modeling the median value of each coffee category and applied a 20% false discovery rate criterion to P-values.

Background: Coffee consumption has been reported to be inversely associated with hepatocellular carcinoma (HCC), the most common type of liver cancer. Caffeine has chemopreventive properties, but whether caffeine is responsible for the coffee-HCC association is not well studied. In addition, few studies have examined the relationship by sex, and no studies have examined whether there is an association between coffee and intrahepatic cholangiocarcinoma (ICC), the second most common type of liver cancer.

Results: Higher coffee consumption was associated with lower risk of HCC (HR>3 cups/day vs. non-drinker, 0.73; 95% CI, 0.53-0.99; ptrend cups/day=<0.0001). More notable reduced risk was seen among women than men (pinteraction=0.07). Women who consumed more than three cups of coffee per day were at a 54% lower risk of HCC (HR, 0.46; 95% CI, 0.26-0.81), whereas men had more modest reduced risk of HCC (HR, 0.93; 95% CI, 0.63-1.37). The associations were stronger for caffeinated coffee (HR>3 cups/day vs. non-drinker, 0.71, 95% CI, 0.50-1.01) than decaffeinated coffee (HR, 0.92; 95% CI, 0.55-1.54). There was no relationship between coffee consumption and ICC.

Conclusions: These findings suggest that, in a U.S. population, coffee consumption is associated with reduced risk of HCC. Impact: Further research into specific coffee compounds and mechanisms that may account for these associations is needed.

This is a dose-response (DR) meta-analysis to evaluate the association of coffee consumption on endometrial cancer (EC) risk. A total 1,534,039 participants from 13 published articles were added in this meta-analysis. The RR of total coffee consumption and EC were 0.80 (95% CI: 0.74-0.86). A stronger association between coffee intake and EC incidence was found in patients who were never treated with hormones, 0.60 (95% CI: 0.50-0.72), and subjects with a BMI ≥25 kg/m(2), 0.57 (95% CI: 0.46-0.71). The overall RRs for caffeinated and decaffeinated coffee were 0.66 (95% CI: 0.52-0.84) and 0.77 (95% CI: 0.63-0.94), respectively. A linear DR relationship was seen in coffee, caffeinated coffee, decaffeinated coffee and caffeine intake. The EC risk decreased by 5% for every 1 cup per day of coffee intake, 7% for every 1 cup per day of caffeinated coffee intake, 4% for every 1 cup per day of decaffeinated intake of coffee, and 4% for every 100 mg of caffeine intake per day. In conclusion, coffee and intake of caffeine might significantly reduce the incidence of EC, and these effects may be modified by BMI and history of hormone therapy.

Association between coffee consumption and the risk of oral cancer: a meta-analysis of observational studies.

OBJECTIVE: Quantification of the association between the coffee consumption and risk of oral cancer is still conflicting. Thus, we conducted a meta-analysis to summarize the evidence from epidemiological studies of coffee consumption with the risk of oral cancer.

METHODS: Pertinent studies were identified by a search of PubMed and Web of Knowledge to March 2015. The random effect model was used. Sensitivity analysis and publication bias were conducted.

BACKGROUND: Several epidemiological studies have determined the associations between coffee intake level and skin cancer risk; however, the results were not yet conclusive. Herein, we conducted a systematic review and meta-analysis of the cohort and case-control studies for the association between coffee intake level and malignant melanoma (MM) risk.

METHODS: Studies were identified through searching the PubMed and MEDLINE databases (to November, 2015). Study-specific risk estimates were pooled under the random-effects model.

CONCLUSIONS: This meta-analysis suggested that caffeinated coffee might have chemo-preventive effects against MM but not decaffeinated coffee. However, larger prospective studies and the intervention studies are warranted to confirm these findings.

Coffee consumption and risk of gastric cancer: an updated meta-analysis.

BACKGROUND AND OBJECTIVES: Coffee is one of the most widely consumed beverages worldwide, and many studies have investigated the association between coffee consumption and gastric cancer. However, the results are inconsistent. We conducted a systematic analysis of relevant population studies to derive a more precise estimation.

RESULTS: Twenty two studies (9 cohort and 13 case-control studies) involving 7,631 cases and 1,019,693 controls were included. The summary RR of gastric cancer was 0.94 (95% CI: 0.80-1.10) for the highest category of coffee consumption compared with the lowest category, and 0.93 (95% CI: 0.88-0.99) for coffee drinkers compared with nondrinkers. We stratified the population by coffee consumption. The pooled RR for the population with <1 cup/day, 1-2 cups/day and 3-4 cups/day coffee consumption compared with nondrinkers were 0.95 (95% CI: 0.84-1.08), 0.92 (95% CI: 0.82-1.03) and 0.88 (95% CI: 0.76-1.02), respectively, indicating that an increase in coffee consumption was associated with a decreased risk of gastric cancer. Furthermore, we stratified the studies by design, sex, population and time. A significant association between coffee intake and decreased gastric cancer risk was shown in case-control studies (RR=0.85, 95% CI: 0.77-0.95) and among the studies published over the last ten years (RR=0.88, 95% CI: 0.77-1.00).

Coffee consumption and risk of hepatocellular carcinoma: a meta-analysis of eleven epidemiological studies.

Growing evidence has shown that coffee consumption is inversely related with the risk of hepatocellular carcinoma. It is suggested that caffeine maintains strong antioxidative activity. With this property, coffee intake may lead to the inhibition of cell proliferation of liver cancer cells; also, some compounds contained in coffee can reduce the genotoxicity of aflatoxin B1 in vitro and lower the damage caused by some carcinogens. A computerized search was performed in PubMed to identify relevant articles published before August 2015. Eleven relevant studies were included with a total of 2,795 cases and 340,749 control subjects. According to the meta-analysis we performed, the pooled odds ratio (OR) from all included studies was 0.49 (95% confidence interval [CI] =0.46-0.52). The subgroup analysis indicated that the pooled ORs for Asian studies and other populations were 0.27 (95% CI =0.23-0.31) and 0.82 (95% CI =0.77-0.87), respectively. The overall pooled OR for high consumption was decreased to 0.21 (95% CI =0.18-0.25) and significance was observed. Among other populations, the pooled OR of subjects with high coffee consumption was 0.65 (95% CI =0.56-0.73) compared to the nondrinker. The corresponding OR of five Asian studies was 0.13 (95% CI =0.09-0.17). The findings from this meta-analysis further confirmed the inverse association between the coffee consumption and hepatocellular carcinoma risk with quantitative evidence. The protective effect can be detected among healthy population and patients with chronic liver diseases, and the consumption can also prevent the development of liver cirrhosis.

Coffee and green tea consumption in relation to brain tumor risk in a Japanese population.

Few prospective studies have investigated the etiology of brain tumor, especially among Asian populations. Both coffee and green tea are popular beverages, but their relation with brain tumor risk, particularly with glioma, has been inconsistent in epidemiological studies. In this study, we evaluated the association between coffee and greed tea intake and brain tumor risk in a Japanese population. We evaluated a cohort of 106,324 subjects (50,438 men and 55,886 women) in the Japan Public Health Center-based Prospective Study (JPHC Study). Subjects were followed from 1990 for Cohort I and 1993 for Cohort II until December 31, 2012. 157 (70 men and 87 women) newly diagnosed cases of brain tumor were identified during the study period. Hazard ratio (HR) and 95% confidence intervals (95%CIs) for the association between coffee or green tea consumption and brain tumor risk were assessed using a Cox proportional hazards regression model. We found a significant inverse association between coffee consumption and brain tumor risk in both total subjects (≥3 cups/day; HR=0.47, 95%CI=0.22-0.98) and in women (≥3 cups/day; HR=0.24, 95%CI=0.06-0.99), although the number of cases in the highest category was small. Furthermore, glioma risk tended to decrease with higher coffee consumption (≥3 cups/day; HR=0.54, 95%CI=0.16-1.80). No association was seen between green tea and brain tumor risk. In conclusion, our study suggested that coffee consumption might reduce the risk of brain tumor, including that of glioma, in the Japanese population.

STUDY DESIGN: In this randomized controlled trial, 114 patients were preoperatively allocated to either postoperative coffee consumption with three times daily (n=58) or routine postoperative care without coffee consumption (n=56). Total abdominal hysterectomy and bilateral salpingo-oophorectomy with systematic pelvic and para-aortic lymphadenectomy (PPL) were performed on all patients as part of complete staging surgery for endometrial, ovarian, cervical, or tubal cancer. The primary outcome measure was the time to the first passage of flatus after surgery. Secondary outcomes were the time to first defecation, time to first bowel movement, and time to tolerance of a solid diet.

RESULTS: The mean time to flatus (30.2±8.0 h vs. 40.2±12.1 h; P < 0.001), mean time to defecation (43.1±9.4 h vs. 58.5±17.0 h; P < 0.001), and mean time to the ability to tolerate food (3.4±1.2 days vs. 4.7±1.6 days; P < 0.001) were all significantly reduced in patients who consumed coffee compared to controls. Mild ileus symptoms were observed in 17 (30.4%) patients in the control group compared to 6 (10.3%) patients in the coffee group (P = 0.01). Coffee consumption was well tolerated and well accepted by patients, and no intervention-related side-effects were observed.

CONCLUSIONS: Coffee consumption after total abdominal hysterectomy and systematic PPL expedites the time to bowel motility and the ability to tolerate food. This simple, cheap, and well-tolerated treatment should be added as an adjunct to the postoperative care of gynecological oncology patients.

Coffee Consumption and Risk of Gallbladder Cancer in a Prospective Study.

Evidence indicates that coffee consumption may reduce the risk of gallstone disease, which is strongly associated with increased risk of gallbladder cancer. The association between coffee consumption and gallbladder cancer incidence was examined in a prospective cohort study of 72 680 Swedish adults (aged 45 - 83 years) who were free of cancer and reported their coffee consumption at baseline. Gallbladder cancers were ascertained by linkage with the Swedish Cancer Register. The data were analyzed using Cox proportional hazards regression models. Statistical tests were two-sided. During 967 377 person-years of follow-up, 74 gallbladder cancer case patients were identified. Compared with consumption of one or less cups of coffee per day, the multivariable hazard ratios were 0.76 (95% confidence interval [CI] = 0.41 to 1.41) for two cups per day, 0.50 (95% CI = 0.24 to 1.06) for three cups per day, and 0.41 (95% CI = 0.20 to 0.83) for four or more cups per day. In conclusion, coffee consumption is associated with a reduced risk of gallbladder cancer.

Aim: A dose-response meta-analysis was conducted in order to summarize the evidence from prospective cohort studies regarding the association between coffee intake and breast cancer risk.

Methods: A systematic search was performed in electronic databases up to March 2017 to identify relevant studies; risk estimates were retrieved from the studies and linear and non-linear dose-response analysis modelled by restricted cubic splines was conducted. A stratified and subgroup analysis by menopausal and estrogen/progesterone receptor (ER/PR) status, smoking status and body mass index (BMI) were performed in order to detect potential confounders.

Results: A total of 21 prospective studies were selected either for dose-response, the highest versus lowest category of consumption or subgroup analysis. The dose-response analysis of 13 prospective studies showed no significant association between coffee consumption and breast cancer risk in the non-linear model. However, an inverse relationship has been found when the analysis was restricted to post-menopausal women. Consumption of four cups of coffee per day was associated with a 10% reduction in postmenopausal cancer risk (relative risk, RR 0.90; 95% confidence interval, CI 0.82 to 0.99). Subgroup analyses showed consistent results for all potential confounding factors examined.

Conclusions: Findings from this meta-analysis may support the hypothesis that coffee consumption is associated with decreased risk of postmenopausal breast cancer.

Be well!

JP

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